The present invention relates to an apparatus and method for forming green tires. More particularly, the present invention relates to an improvement of an apparatus and method for forming green tires using transfer equipment which is positioned between a green tire former and a belt former that is moved therebetween. The apparatus a belt-tread assembly formed by the belt former to set assembly on a periphery of a green carcass to be toroidally shaped by the green tire former.
In a conventional green tire forming technique, for example, as shown in FIG. 12, a belt-tread assembly is formed by a belt former 101 on one side. A green carcass is formed by a green tire former 102 on the other side. Beads are held by bead setting mechanisms 103A, 103B, respectively and moved to predetermined positions on the tire former 102 by air cylinders 104A, 104B. The beads are then fixed with the green carcass by extending the diameters of bead lock mechanisms integrated in first and second shoulder formers 106A, 106B. The belt-tread assembly formed by the belt former 101 is positioned on the periphery of the green carcass by a transferring mechanism 105. The green carcass is toroidally shaped by feeding shaping air inside the green carcass while moving both shoulder formers 106A, 106B inwardly toward each other using a driving mechanism (not shown). The belt-tread assembly is then attached to the green carcass. Both edges of the carcass ply are turned up around the beads by expanding ply turn-up bladders provided to the first and the second shoulder formers 106A, 106B. The ply turn-up bladders are further pressed from outside in both directions by expanding the pressing bladders (for example, Japanese Examined Patent Publication No. 70548/1984) provided outside of the ply turn-up bladders. The turned-up portion and the side walls of the carcass ply are firmly fixed to the body of the carcass to complete a green tire.
A conventional apparatus employed in this kind of green tire forming technique is generally mechanically complicated as mentioned above. In a conventional apparatus, for example, the bead setting mechanisms (the bead setters 103A, 103B) for setting beads at predetermined positions on a green carcass arranged on a green tire former, and the pressing mechanisms (pressing bladders) for pressing ply turn-up bladders from sides thereof, are independently and separately provided.
Also, in the conventional tire forming apparatus, in order to hold and to release a belt-tread assembly, the transferring mechanism utilizes a plurality of segments forming an inner surface corresponding to the outer surface of the assembly, and a bladder or an air cylinder operated with air pressure for increasing or decreasing the inner diameter of an annular portion constituted by the segments, namely for extension or retraction of the segments. Accordingly, in holding the belt-tread assembly to position it at the periphery of the green carcass and combining the assembly with the green carcass which is shaped toroidally, the air is pressurized to retreat the segments when the belt-tread assembly is pushed outward by expansion force of the green carcass generated by inner pressure for shaping and the resulting pressurizing force is applied to the bladder or the air cylinder, the drive of the segments, via the segments. As a result, the outer diameter of the belt and tread are expanded undesirably, so that there arises a problem in that a defective tire is produced. Further, when the belt-tread assembly is combined with the green carcass, as illustrated inside the dotted circle C in FIG. 11, neither edge of the assembly is firmly adhered to the green carcass, making it necessary to press the edges by a stitcher afterward. As a result, there also arises a problem in that, when pressurizing, the breaker edge is deformed, or cords are snaked or separated whereby the uniformity of a tire is badly influenced.
Further, in order to remove a produced green tire from the tire former, an exclusive take-out mechanism is provided separately, or the segments of the transferring mechanism are utilized. However, there are such drawbacks that the apparatus becomes complicated when the take-out mechanism is separately provided, and it takes much time for taking out the produced green tire from the transferring mechanism when the segments are used.